/*
 * Copyright 2009-2013 by The Regents of the University of California
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * you may obtain a copy of the License from
 * 
 *     http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package edu.uci.ics.hyracks.storage.am.lsm.invertedindex.ondisk;

import edu.uci.ics.hyracks.api.dataflow.value.ITypeTraits;
import edu.uci.ics.hyracks.dataflow.common.data.accessors.ITupleReference;
import edu.uci.ics.hyracks.storage.am.lsm.invertedindex.api.IInvertedListBuilder;

public class FixedSizeElementInvertedListBuilder implements IInvertedListBuilder {
    private final int listElementSize;
    private int listSize = 0;

    private byte[] targetBuf;
    private int pos;

    public FixedSizeElementInvertedListBuilder(ITypeTraits[] invListFields) {
        int tmp = 0;
        for (int i = 0; i < invListFields.length; i++) {
            tmp += invListFields[i].getFixedLength();
        }
        listElementSize = tmp;
    }

    @Override
    public boolean startNewList(ITupleReference tuple, int tokenField) {
        if (pos + listElementSize > targetBuf.length) {
            return false;
        } else {
            listSize = 0;
            return true;
        }
    }

    @Override
    public boolean appendElement(ITupleReference tuple, int numTokenFields, int numElementFields) {
        if (pos + listElementSize > targetBuf.length) {
            return false;
        }

        for (int i = 0; i < numElementFields; i++) {
            int field = numTokenFields + i;
            System.arraycopy(tuple.getFieldData(field), tuple.getFieldStart(field), targetBuf, pos,
                    tuple.getFieldLength(field));
        }

        listSize++;
        pos += listElementSize;

        return true;
    }

    @Override
    public void setTargetBuffer(byte[] targetBuf, int startPos) {
        this.targetBuf = targetBuf;
        this.pos = startPos;
    }

    @Override
    public int getListSize() {
        return listSize;
    }

    @Override
    public int getPos() {
        return pos;
    }
}
